Exercise effect on electromyographic activity of the vastus medialis oblique and vastus lateralis muscles

The purpose of this study was to determine whether the vastus medialis oblique muscle (VMO) had greater electrical activity than the vastus lateralis muscle (VL) when hip adduction and medial (internal) tibial rotation exercises were performed. Electrical activity of the VMO and VL was measured on 25 healthy subjects during maximal-effort isometric contractions of hip adduction and medial tibial rotation. The results showed that the electromyographic activity of the VMO was significantly greater than that of the VL during the hip adduction exercise. Differences noted with medial tibial rotation were not significant. The results suggest that the VMO may be selectively activated by performing hip adduction exercises. Resistive hip adduction exercises, therefore, may be advisable in the treatment of patients with lateral malalignment of the patella with accompanying pain or instability.     

The effect of hip abduction on the EMG activity of vastus medialis obliquus, vastus lateralis longus and vastus lateralis obliquus in healthy subjects

Study design  

Controlled laboratory study.     

Temporal activity of vastus medialis obliquus and vastus lateralis in symptomatic knee osteoarthritis

OBJECTIVE: Knee osteoarthritis has a major impact on quadriceps function, yet its effect on the specific temporal recruitment of vastus medialis obliquus and vastus lateralis is unknown. The aim of this study was to determine the electromyographic onset of vastus medialis obliquus activity relative to that of vastus lateralis in individuals with symptomatic knee osteoarthritis and in an asymptomatic control group during the functional task of stair climbing. DESIGN: Cross-sectional, comprising 41 participants with symptomatic knee osteoarthritis and 33 controls matched for age, sex, and body mass. RESULTS: No significant differences were detected in the timing of onset of vastus medialis obliquus relative to that of vastus lateralis between the osteoarthritis and control groups. Radiographic osteoarthritis severity, presence of patellofemoral joint disease, and pain intensity did not seem to influence the temporal relationship of the vastii in the osteoarthritis group. CONCLUSION: The presence of symptomatic, radiographic knee osteoarthritis is not associated with deficits in the temporal recruitment of vastus medialis obliquus and vastus lateralis during stair climbing. This implies that selective retraining of the individual components of the quadriceps is not indicated in rehabilitation programs for patients with this disease.     

Activation of the vastus medialis oblique and vastus lateralis muscles in asymptomatic subjects during the sit-to-stand procedure

[Purpose] The purpose of this study was to examine the vastus medialis oblique to vastus lateralis ratio in two pelvic tilt positions while performing the sit-to-stand task. [Subjects and Methods] Activation of the vastus medialis oblique and the vastus lateralis muscles of 46 healthy subjects (25 males, 21 females) were recorded by surface electromyography during the STS task with anterior pelvic tilt (sit with thoracolumbar spine extended and pelvis in an anterior tilt) and neutral pelvic tilt (sit with thoracolumbar spine relaxed and pelvis in the neutral tilt position) positions. Changes in vastus medialis oblique, vastus lateralis activation and the vastus medialis oblique/vastus lateralis ratio were analyzed. [Results] Vastus medialis oblique and vastus lateralis muscle activation significantly increased in neutral pelvic tilt position, but the vastus medialis oblique/vastus lateralis ratio was not statistically different. [Conclusion] The sit-to-stand procedure with neutral pelvic tilt position increased activation of the vastus medialis oblique and vastus lateralis, usefully strengthening the quadriceps, but did not selectively activate the vastus medialis oblique muscle.Key words: Anterior pelvic tilt, Neutral pelvic tilt, Sit-to-stand task     

An electromyographical study to investigate the effects of patellar taping on the vastus medialis/vastus lateralis ratio in asymptomatic participants

It is commonly theorised that patellofemoral pain syndrome (PFPS) is caused by maltracking due to vastus medialis (VM) weakness relative to the vastus lateralis (VL). Despite this being a controversial theory, patellar taping is a commonly used technique that purports to correct this muscle imbalance by increasing the VM/VL ratio. The effects of different forms of taping on vasti muscle activity are still not known. The objective of this study was to investigate the effects of three different types of patellar taping on the VM/VL ratio in asymptomatic university students. Each participant performed a set of four single-legged squats under four separate taping conditions: A) medial, B) lateral, C) neutral, and D) no-tape. The condition sequence was randomised. The main outcome measure was the normalised VM/VL ratio, assessed by using surface electromyography. Secondary outcome measures were the normalised EMG activity of the VM and the VL. A convenience sample of 24 (17 females) students (22 +/- 10 years, M +/- SD) completed this study. The lateral taping condition produced small but significantly greater VM/VL ratios than the medial (p = 0.007) and neutral (p = 0.007) but not the no-tape (p = 0.123) condition. There were no significant differences between the medial, neutral, and no-tape conditions. These results question whether patellar taping can impart a clinically significant effect on the VM/VL ratio. The results of this study cannot be directly extrapolated to a patient population, and further research in the PFPS population is required before clinical recommendations can be made.     

The effect of stretching exercises on the fibre angle of the vastus lateralis and vastus medialis oblique: an ultrasound study

[Purpose] To investigate the effects of a seven-week quadriceps stretching program on the muscle fibre orientation of the vastus medialis oblique and vastus lateralis in the lower limbs by ultrasound imaging. [Participants and Methods] Twenty-seven healthy, physically fit, asymptomatic females and males (age 21.5 ± 1.3, Tegner activity level score ≥4) were recruited. Their initial vastus medialis oblique and vastus lateralis fibre angles were determined using ultrasound. They then undertook a seven-week quadriceps stretching program, 3 sets of stretches to be performed on both lower limbs, 3 times a week on 3 separate days. One volunteer was assigned as an intra-rater control and did not take part in the stretching program. The vastus lateralis and vastus medialis oblique fibre angles were measured again on completion of the exercise regime. [Results] A statistically significant decrease in muscle fibre angle was observed in both the right and left vastus medialis oblique, and the right and left vastus lateralis. [Conclusion] A 7-week stretching program can result in a significant decrease in muscle fibre angle in both the vastus medialis oblique and the vastus lateralis. This can help in understanding the effects of prescribed stretching exercises on athletic patients with PFP.     

An electromyographical study to investigate the effects of patellar taping on the vastus medialis/vastus lateralis ratio in asymptomatic participants

It is commonly theorised that patellofemoral pain syndrome (PFPS) is caused by maltracking due to vastus medialis (VM) weakness relative to the vastus lateralis (VL). Despite this being a controversial theory, patellar taping is a commonly used technique that purports to correct this muscle imbalance by increasing the VM/VL ratio. The effects of different forms of taping on vasti muscle activity are still not known. The objective of this study was to investigate the effects of three different types of patellar taping on the VM/VL ratio in asymptomatic university students. Each participant performed a set of four single–legged squats under four separate taping conditions: A) medial, B) lateral, C) neutral, and D) no-tape. The condition sequence was randomised. The main outcome measure was the normalised VM/VL ratio, assessed by using surface electromyography.

Secondary outcome measures were the normalised EMG activity of the VM and the VL. A convenience sample of 24 (17 females) students (22 ± 10 years, M ± SD) completed this study. The lateral taping condition produced small but significantly greater VM/VL ratios than the medial (p = 0.007) and neutral (p = 0.007) but not the no-tape (p = 0.123) condition. There were no significant differences between the medial, neutral, and no-tape conditions. These results question whether patellar taping can impart a clinically significant effect on the VM/VL ratio. The results of this study cannot be directly extrapolated to a patient population, and further research in the PFPS population is required before clinical recommendations can be made.     

Effects of visibility and types of the ground surface on the muscle activities of the vastus medialis oblique and vastus lateralis

[Purpose] The purpose of this study was to compare the effects of visibility and types of ground surface (stable and unstable) during the performance of squats on the muscle activities of the vastus medialis oblique (VMO) and vastus lateralis (VL). [Subjects and Methods] The subjects were 25 healthy adults in their 20s. They performed squats under four conditions: stable ground surface (SGS) with vision-allowed; unstable ground surface (UGS) with vision-allowed; SGS with vision-blocked; and UGS with vision-blocked. The different conditions were performed on different days. Surface electromyogram (EMG) values were recorded. [Results] The most significant difference in the activity of the VMO and VL was observed when the subjects performed squats on the UGS, with their vision blocked. [Conclusion] For the selective activation of the VMO, performing squats on an UGS was effective, and it was more effective when subjects’ vision was blocked.Key words: Vision, Unstable, VMO     

The vastus medialis oblique:vastus lateralis electromyographic intensity ratio does not differ by gender in young participants without knee pathology

Objectives

To investigate whether there was a gender difference in the intensity of electromyographic (EMG) activity in vastus medialis oblique (VMO) relative to vastus lateralis (VL).

Design

A cross-sectional observational study measuring EMG activity during stepping down from a step and during straight leg raise exercises.

Setting

University campus laboratory.

Participants

Two groups of healthy participants were tested, one female (mean age 23.5 years, n = 15) and one male (mean age 23.5 years, n = 15).

Main outcome measures

Surface EMG activity (sampling rate 1000 Hz) was recorded from VMO and VL of the dominant limb during five repetitions of a step down activity and five repetitions of a straight leg raise exercise. The average intensity of the rectified and smoothed EMG activity from each activity was normalised to that elicited in a maximal quadriceps setting exercise. The ratio of normalised VMO:VL EMG intensity levels was calculated.

Results

The median difference in the VMO:VL ratio between the groups was 0.11 [approximate 95% confidence interval (CI) −0.62 to 1.00] during step down and −0.07 (approximate 95% CI −0.26 to 0.20) during straight leg raise. Using Mann Whitney U-tests, these differences were not statistically significant (P = 0.648 and 0.619, respectively).

Conclusions

This study found no gender difference in the VMO:VL EMG intensity ratio in asymptomatic participants. This suggests that the difference in incidence of patellofemoral pain syndrome between genders is not influenced by quadriceps intensity ratios, when participants are asymptomatic.     

A novel method for measuring electromechanical delay of the vastus medialis obliquus and vastus lateralis

Electromechanical delay (EMD) of the vastus medialis obliquus (VMO) and vastus lateralis (VL) is determined by measuring the interval between the time of onset of muscle activities and the time of onset of mechanical output. However, individual mechanical output of the VMO or the VL cannot be obtained with the conventional method because of the knee extension force as the mechanical output. Therefore, the objective of the present study was to develop a new method for measuring EMD of the VMO and VL individually. Twelve healthy volunteers participated in the experiment. The motor point of the target muscle was electrically stimulated to evoke a muscle twitch. Simultaneously, the electrical stimulation signal was transmitted to ultrasound apparatus via the electrocardiography input channel. The ultrasound apparatus was used to capture the patellar movement elicited by the muscle twitch. EMD was measured from the onset of the electrical stimulation to the onset of patellar movement. The results showed that the intraclass correlation coefficients for the reproducibility of the EMD measurements of the VMO and VL were greater than 0.8. The EMDs of the VMO and VL were 18.3 +/- 2.2 ms and 24.8 +/- 5.8 ms, respectively. This new method provides a more precise measurement of EMD in the VMO and VL than does the conventional method because of the use of patellar movement as the mechanical output.     

Delayed onset of electromyographic activity of vastus medialis obliquus relative to vastus lateralis in subjects with patellofemoral pain syndrome

OBJECTIVE: To determine whether electromyographic (EMG) onsets of vastus medialis obliquus (VMO) and vastus lateralis (VL) are altered in the presence of patellofemoral pain syndrome (PFPS) during the functional task of stair stepping. DESIGN: Cross-sectional. SETTING: University laboratory. PATIENTS: Thirty-three subjects with PFPS and 33 asymptomatic controls. INTERVENTIONS: Subjects ascended and descended a set of stairs-2 steps, each 20-cm high-at usual stair-stepping pace. EMG readings of VMO and VL taken on middle stair during step up (concentric contraction) and step down (eccentric contraction). MAIN OUTCOME MEASURES: Relative difference in onset of surface EMG activity of VMO compared with VL during a stair-stepping task. EMG onsets were determined by using a computer algorithm and were verified visually. RESULTS: In the PFPS population, the EMG onset of VL occurred before that of VMO in both the step up and step down phases of the stair-stepping task (p <.05). In contrast, no such differences occurred in the onsets of EMG activity of VMO and VL in either phase of the task for the control subjects. CONCLUSION: This finding supports the hypothesized relationship between changes in the timing of activity of the vastimuscles and PFPS. This finding provides theoretical rationale to support physiotherapy treatment commonly used in the management of PFPS.     

Vastus lateralis and vastus medialis obliquus muscle activity during the application of inhibition and facilitation taping techniques

OBJECTIVE: To evaluate the effect of inhibition and facilitation taping techniques on the activity of vastus lateralis and vastus medialis obliquus. DESIGN: Repeated-measures design. SETTING: Laboratory in an educational institution. SUBJECTS: Thirty healthy females aged between 18 and 23 years. INTERVENTION: Subjects were tested during the application of inhibition tape, facilitation tape and no tape to vastus lateralis in random order. MAIN OUTCOME MEASURES: Electromyographic activity of vastus lateralis and vastus medialis obliquus during stair descent was recorded using bipolar surface electrodes. RESULTS: Electromyographic activity of vastus lateralis and vastus medialis obliquus during the application of inhibition tape or facilitation tape did not alter significantly compared with no tape condition. CONCLUSIONS: Taping designed to inhibit or facilitate muscle activity via sensory stimulation does not affect vastus lateralis or vastus medialis obliquus activity in healthy subjects. Further investigation is required to find a means of muscle taping that could be recommended as an intervention for patients with patellofemoral pain syndrome.     

Patellar taping does not affect the onset of activities of vastus medialis obliquus and vastus lateralis before and after muscle fatigue

OBJECTIVE: This study examined the immediate effect of patellar taping with a standard force on the onset of vastus medialis obliquus and vastus lateralis activities before and after muscle fatigue in able-bodied subjects. DESIGN: This study tested 29 mature able-bodied subjects. The surface electromyographic onset time of their vastus medialis obliquus and vastus lateralis was measured after a posteroanterior perturbation at the knee in a single-legged standing position. The measurements were taken under three conditions in random order of true patellar taping, sham patellar taping, and no patellar taping. Afterward, subjects performed a knee-extension exercise until their quadriceps fatigued, and the above tests were repeated to test the effect of fatigue on the outcome. RESULTS: There was no statistically significant difference with patellar taping on the electromyographic onset time of the vastus medialis obliquus and vastus lateralis compared with the placebo-taping and no-taping conditions (P = 0.455). There was no statistically significant difference in onset of vastus medialis obliquus and vastus lateralis muscles before and after muscle fatigue (P = 0.304). CONCLUSIONS: The present study suggests that patellar taping does not enhance the temporal activation of vastus medialis obliquus in both fatigue and nonfatigue conditions on able-bodied subjects.     

The effects of squatting with visual feedback on the muscle activation of the vastus medialis oblique and the vastus lateralis in young adults with an increased quadriceps angle

[Purpose] The purpose of this study was to identify the effects of performing squat exercises with visual feedback on the activation of the vastus medialis oblique (VMO) and vastus lateralis (VL) muscles in young adults with an increased quadriceps angle (Q-angle). [Subjects] This study used a motion analysis program (Dartfish, Switzerland) to select 20 young adults with an increased Q-angle, who were then divided into a squat group that received visual feedback (VSG, n=10) and a squat group that received no visual feedback (SG, n=10). [Methods] The intensity of exercises was increased every two weeks over a six-week exercise period in both groups. A visual marker was attached to the patella of the subjects in the VSG, and they then performed squat exercises with a maximum of 90° of knee flexion within a route marked on a mirror. The SG performed squat exercises with a maximum 90° of knee flexion without attaching a visual feedback device. [Results] Analysis of the muscle activation due to 90° squat exercises indicated that both groups had statistically significant increases in activation of the VL. The VSG exhibited statistically significant increases in activation of the VMO. [Conclusion] This study confirmed that squat exercises with visual feedback are effective in activation of the VMO and VL muscles. The findings are meaningful in terms of preventing the occurrence of patellofemoral pain.Key words: Q-angle, Visual feedback squat exercise, VMO     

Effects of squats accompanied by hip joint adduction on the selective activity of the vastus medialis oblique

[Purpose] This study evaluated the effective selective activation method of the vastus medialis oblique for knee joint stabilization in patients with patellofemoral pain syndrome. [Subjects and Methods] Fifteen healthy college students (9 males, 6 females); mean age, height, and weight: 22.2 years, 167.8 cm, and 61.4 kg, respectively) participated. The knee angle was held at 60°. Muscle activities were measured once each during an ordinary squat and a squat accompanied by hip joint adduction. The muscle activities of the vastus medialis oblique and vastus lateralis were measured by electromyography for five seconds while maintaining 60° knee flexion. Electromyography signals were obtained at a sampling rate of 1,000 Hz and band pass filtering at 20–50 Hz. The obtained raw root mean square was divided by the maximal voluntary isometric contraction and expressed as a percentage. The selective activity of the vastus medialis oblique was assessed according to the muscle activity ratio of the vastus medialis oblique to the vastus lateralis. [Results] The activity ratio of the vastus medialis oblique was higher during a squat with hip joint adduction than without. [Conclusion] A squat accompanied by hip joint adduction is effective for the selective activation of the vastus medialis oblique.Key words: Patellofemoral pain syndrome, Vastus medialis oblique, Squat     

Reliability of ultrasonographic measurement of the architecture of the vastus lateralis and gastrocnemius medialis muscles in older adults

Objective: To determine the test‐retest reliability of measurements of thickness, fascicle length (L_f) and pennation angle (θ) of the vastus lateralis (VL) and gastrocnemius medialis (GM) muscles in older adults. Participants: Twenty‐one healthy older adults (11 men and ten women; average age 68·1 ± 5·2 years) participated in this study. Methods: Ultrasound images (probe frequency 10 MHz) of the VL at two sites (VL site 1 and 2) were obtained with participants seated with knee at 90º flexion. For GM measures, participants lay prone with ankle fixed at 15º dorsiflexion. Measures were taken on two separate occasions, 7 days apart (T1 and T2). Results: The ICCs (95% CI) were: VL site 1 thickness = 0·96(0·90–0·98); VL site 2 thickness = 0·96(0·90–0·98), VL θ = 0·87(0·68–0·95), VL L_f = 0·80(0·50–0·92), GM thickness = 0·97(0·92–0·99), GM θ = 0·85(0·62–0·94) and GM L_f =0·90(0·75–0·96). The 95% ratio limits of agreement (LOAs) for all measures, calculated by multiplying the standard deviation of the ratio of the results between T1 and T2 by 1·96, ranged from 10·59 to 38·01%. Conclusion: The ability of these tests to determine a real change in VL and GM muscle architecture is good on a group level but problematic on an individual level as the relatively large 95% ratio LOAs in the current study may encompass the changes in architecture observed in other training studies. Therefore, the current findings suggest that B‐mode ultrasonography can be used with confidence by researchers when investigating changes in muscle architecture in groups of older adults, but its use is limited in showing changes in individuals over time.     

Comparison of vastus medialis obliquus: vastus lateralis muscle integrated electromyographic ratios between healthy subjects and patients with patellofemoral pain

The purpose of this study was to compare vastus medialis obliquus:vastus lateralis muscle (VMO:VL) integrated electromyographic (IEMG) ratios of healthy subjects and patients with unilateral patellofemoral pain (PFP) under isotonic and isometric quadriceps femoris muscle contraction conditions. Subjects ranging in age from 18 to 35 years (mean = 28.06, SD = 5.97) were assigned to one of three groups on the basis of type of knee condition. In group 1, which consisted of seven healthy control subjects with no history of knee pathology, both knees were tested. In group 2, which consisted of nine patients with unilateral PFP, only the painful knee was tested. In group 3, which consisted of the same nine patients who comprised group 2, only the nonpainful knee was tested. Nonnormalized and normalized VMO:VL IEMG ratios were computed for ascending stairs, descending stairs, submaximal isometric contraction, and maximal isometric contraction (nonnormalized only). A two-way analysis of variance for repeated measures indicated VMO:VL ratios for isotonic stair-climbing activities were significantly greater than VMO:VL ratios for isometric contractions. Nonnormalized VMO:VL ratios in group 1 were significantly greater than nonnormalized VMO:VL ratios in the other two groups. Patients with PFP may have abnormal VMO:VL activation patterns, and isotonic quadriceps femoris muscle exercise may elicit more favorable muscle activation patterns than isometric exercise for patients with PFP.     

Effects of the slow speed-targeting squat exercise on the vastus medialis oblique/vastus lateralis muscle ratio

[Purpose] This study investigated the effects of the slow speed-targeting squat exercise on the vastus medialis oblique/vastus lateralis ratio. [Subjects] Ten asymptomatic men were recruited. [Methods] The EMG activities of the vastus medialis oblique and vastus lateralis muscles were recorded using surface electrodes. The subject performed the squat exercise under 3 different conditions. [Results] The vastus medialis oblique/vastus lateralis ratio in condition 2 (1.5 ± 0.7) was significantly higher than that in conditions 1 and 3 (1.0 ± 0.5, 1.1 ± 0.8, respectively) [Conclusion] Therefore, an effectively slow movement speed is recommended for selective strengthening of vastus medialis oblique using a slow speed-targeting device that provides biofeedback.Key words: Slow movement speed, Squat exercise, VMO